Method of mutually aligning bodies and position-measuring sensor therefor

ABSTRACT

The invention concerns a method of mutually aligning bodies, in particular for the parallel alignment of shafts, rollers and the like, which can be carried out economically and simply in a substantially shorter time than the known methods used for this purpose. The essence of the invention is the use of an optical gyroscope, for example a fiber-optic gyroscope ( 5 ), in a position-measuring sensor ( 4 ) which is placed in turn in a specific position on the bodies ( 1, 2, 3 ) to be mutually aligned for a given time interval to measure the relative angular position. The position-measuring sensor ( 4 ) supplies angle data on the basis of which it can be established whether, and if necessary which, position corrections have to be made at the bodies in order to bring them into the desired state of alignment. The invention further concerns a position-measuring sensor which can be used in the method according to the invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for mutually aligning bodies, inparticular for the parallel alignment of shafts, rollers and the like,and to a position measuring sensor for carrying out the method.

To date, optical measuring arrangements such as theodolites,autocollimators, interferometers and lasers and, by way of furtherancillary means, markers, targets, pentaprisms, ridge prisms, tripleprisms, mirrors, detectors, stands and the like have been used in a verytime consuming manner for angle measurement for the purpose of themutual alignment of bodies, e.g. of axles, rollers, rolls, spindles,rotary furnaces and the like, their drives such as chains, belts,transmissions, universal joints and the like as well as their associatedcarrier elements such as support frame, machine beds, foundations etc.,with measurement accuracies of below 1 mm/m.

2. Description of Related Art

The object of the invention is to specify a method by which the anglemeasurement of bodies to be mutually aligned can be performed with anexpenditure of time, and in some cases also a design complexity, whichis substantially less than in the case of the known devices andancillary means for this purpose.

In contrast to the known methods, in which as a rule a plurality ofdevices and ancillary means have to be secured to the bodies to bemeasured, aligned with respect to one another and then moved in commonwith bodies in a measurement cycle, in the case of the inventive methodit is merely necessary for a single position measuring sensor which issimple to handle and which is equipped with an optical gyroscope to beapplied in a few measurement positions to in each case two bodies to bealigned with respect to one another and to be read off directly orelectronically, with respect to gyro angle and inclination, in order tobe able to establish whether any position corrections at all, and, ifso, which ones are necessary in order to achieve the desired alignmentThe operator's measurement time required for this is far shorter thanthat which is necessary when using the known devices and ancillary meansA reduction in the operator's measurement time of up to 95% is to beexpected.

The invention is based on the finding that optical gyroscopes aredistinguished by a very low noise level thus, by way of example a knownfiber optic gyroscope (referred to in the English literature inabbreviated form as FOG) has a noise level of only 0.1° per root hourwhen using a fiber ring having a diameter of approximately 80 mm—andthat, on the basis of such a low noise level with the observance of atime interval measuring in the order of magnitude of a few seconds forthe application of the measuring sensor to the two bodies to be alignedfor the purpose of obtaining a pair of measured values, it is possibleto obtain measured values which are absolutely accurate enough, becausein this gyroscope resetting time, which although short is sufficient forpractical purposes, a gyroscope which is appropriately dimensionedaccording to the given possibilities only drifts by a few grad, which issufficient for most measurement problems.

The accuracy of measurement is all the greater, the more rapidly and/ormore frequently the measuring sensor can be reset with its opticalgyroscope

A further object of the invention is to provide a position measuringsensor for determining the spatial position of two bodies with respectto one another, which sensor has a high accuracy of measurement forangle measurements and is particularly suitable for carrying out theinventive method.

In the text which follows, the invention is explained in even greaterdetail with the aid of the drawing, by reference to an illustrativeembodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 diagrammatically shows three bodies to be aligned with respect toone another, as well as a position measuring sensor to be appliedsequentially to these, in perspective representation, and

FIG. 2 diagrammatically shows a preferred embodiment of a positionmeasuring sensor for measuring the relative angular position of thebodies in FIG. 1, likewise in perspective representation.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows, in perspective representation, a first body 1, whichserves as carrier and which, for the sake of simplicity, is representedas a plate, as well as two further bodies 2 and 3 of cylindrical outercontour, which are to be aligned in relation to the first body 1 andwith respect to one another. With an appropriate design in detail, itwould be possible for the body 1 to comprise a machine bed and for thebodies 2 and 3 to comprise rollers, which are mounted on the machine bedto be rotatable about their longitudinal axis and are to be aligned withrespect to their axes of rotation parallel to one another as well as ina defined angular position with respect to a reference surface on themachine bed.

In the illustrative embodiment, the planar lateral end face 1 a servesas reference surface on the body 1, and the longitudinal axes of theroller-shaped bodies 2 and 3 are to be aligned parallel to one anotherand to the reference surface 1 a.

As represented in FIG. 1, the possibly necessary position correctionvalues for the alignment to the aforementioned desired mutual angularposition are obtained by a position measuring sensor 4 being applied byits contact surface 4 a successively (4-1, 4-2, 4-3) to the referencesurface 1 a on the body 1, parallel to the longitudinal central axis tothe cylindrical periphery of the body 2 and parallel to the longitudinalcentral axis to the cylindrical periphery of the body 3 and, in thiscase, in each instance being held in such a spatial alignment that theplane 5 a of the fiber ring of a fiber optic gyroscope 5 which issituated in the position measuring sensor 4 and which is aligned in adefined manner with respect to the sensor contact surface 4 a extendsparallel to a reference plane in space, e.g. parallel to the horizontalplane. After each application to one of the bodies 1, 2 and 3, the gyroangle measured by the fiber optic gyroscope is read off with respect toa reference direction in the plane of the fiber ring or is output as acorresponding electrical signal by the position measuring sensor to adataprocessing device which is not shown.

Fiber optic gyroscopes are distinguished by an only very small driftangle per unit time It is currently possible in practice to achievedrift angles of a few μrad per root second, so that a gyro angle displayaccuracy which is in most cases quite sufficient for practical purposescan be achieved throughout the measurement process, if it is insuredthat the position measuring sensor is reset between the bodies 1, 2 and3 and read off within a time interval in the order of magnitude of, forexample, 10 to 20 seconds. In this case, it is also possible for exampleto proceed in such a way that firstly a reference position measurementis carried out on the body surface 1 a of the body 1 and as the nextitem a position location measurement is carried out on the periphery ofthe body 2, then another reference position measurement on the bodysurface 1 a , position location and another measurement on the peripheryof the body 3, the predetermined time interval being available for eachresetting.

To determine the mutual alignment of the bodies 1, 2 and 3 in space, itmay be necessary to carry out further reference and position locationmeasurements on the bodies 1, 2 and 3 in a spatial angular position ofthe position measuring sensor 4 parallel to a reference plane whichincludes a defined angle, e.g. 90°, with the reference plane which wasutilized for the first measurements.

FIG. 2 shows diagrammatically, in perspective representation a positionmeasuring sensor 10 which is particularly suitable for carrying out theinventive measuring method and could be used as position measurementsensor 4 in the angle measurement of bodies 1, 2 and 3 in FIG. 1. Thismeasuring sensor 10 is equipped with an optical gyroscope 11, preferablya fiber optic gyroscope, which is fixedly disposed in a sensor housing12. The sensor housing 12 has four outer contact surfaces 12 a- 12 dwhich are parallel to one another in opposite pairs and perpendicular toone another in mutually adjoining pairs, as well as a further contactsurface 12 e which stands perpendicular to all four of theabovementioned contact surfaces. The statements “parallel to oneanother” and “perpendicular to one another”, apply de facto to thecontact surfaces 12 a- 12 e even in circumstances in which these are notcontinuously planar surfaces, but, as represented in FIG. 2, surfaceswhich consist in each instance of two planar surface portions, e.g. 12a′, which enclose a shallow angle with one another. By means of theincorporation of the optical gyroscope in a fixed, defined position intothe position measuring sensor 10, the plane 11 a of its optical ring, inthis case of the fiber ring, is also aligned in a defined manner withrespect to the outer contact surfaces 12 a-12 e on the housing 12 of theposition measuring sensor 10.

Furthermore, the position measuring sensor 10 has a computer interface13 for calibration purposes and measurement data processing, anindication 14 for gyro angle and inclinations, a zero key and indicationswitch-over 15 and an accurate double-action inclinometer 16 toestablish the angular position of the position measuring sensor 10 withrespect to the vertical.

The computer interface 13 makes it possible to transmit the data of thegyro angle and of the inclination which are available in each instancein the applied condition of the position measuring sensor to a computer,not shown, which computes from these data the values of the directionswhich are possibly necessary for the purpose of bringing the bodies 1, 2and 3 which are to be aligned relative to one another into the desiredalignment conditions.

According to the inventive method and with the inventive positionmeasuring sensor, it is also possible to align body axes, body surfacesand the like in a manner other than parallel to one another, e.g.perpendicular with respect to one another, in a simple manner, veryaccurately with a low expenditure of time.

In principle, it is also possible to use optical gyroscopes in the formof laser gyroscopes.

What is claimed is:
 1. An angular position measuring sensor fordetermining a difference of angular position of two bodies with respectto each other, comprising: a) a housing having at least one outercontact surface for mounting on a countersurface of a body; b) at leastone optical gyroscope in the housing, said optical gyroscope having anoptical ring that is contained in a plane that is aligned in a definedmanner relative to the outer contact surface of the housing; and c)means for outputting from the sensor information for aligning the planecontaining the optical ring relative to vertical and an angular positionof the plane relative to a reference direction of the body to bealigned.
 2. The angular position measuring sensor according to claim 1,wherein the optical gyroscope is a fiber-optic gyroscope.
 3. The angularposition measuring sensor according to claim 1, wherein the housing hasa plurality of contact surfaces disposed in a defined relationship withrespect to each other.
 4. The angular position measuring sensoraccording to claim 3, wherein at least one of said contact surfacescomprises a pair of planar surface portions which are at an obtuse anglewith respect to each other for engaging a curved countersurface of thebody to be aligned.
 5. The angular position measuring sensor accordingto claim 1, further comprising a plumb for determining said alignment ofthe plane containing the optical ring relative to vertical.
 6. Theangular position measuring sensor according to claim 1, furthercomprising a plumb for determining alignment of the plane containing theoptical ring relative to vertical.
 7. The angular position measuringsensor according to claim 1, wherein said means for outputting comprisesa computer interface for outputting of data.
 8. The angular positionmeasuring sensor according to claim 1, further comprising a computerinterface for outputting of data.